The subject matter disclosed herein relates to semiconductor structures. More particularly, the subject matter relates to voltage islands in semiconductor structures.
As integrated circuit technologies have advanced, the size of these devices has correspondingly decreased. In particular, as devices are reduced in scale to comply with ever-smaller packaging, tighter constraints are applied to their dimensions and spacings.
Conventional integrated circuit (IC) structures utilize a central chip power system to power all chip logic, which includes chip control logic and special function logic. Because this central chip power system powers the control logic, it must be powered up all the time, and consequently, all other chip logic, including special function logic, must also be powered up all the time (even when not needed to perform any function).
Some types of ICs have multiple power systems, which can be dedicated to certain logic functions that are not used all the time. A dedicated power system for a logic function that is not used can be turned off or never powered up. This type of power management on an IC can be useful to reduce overall IC power consumption. One constraint of such an approach is the amount of time it takes to turn on a power system. Turning on such a power system can typically take microseconds to milliseconds before a desired voltage is established. This is a significant period of time for high-performance IC applications that still want to reduce power consumption, and as a result, this approach may be ineffective. Unfortunately, central power systems and multiple power systems may fail to respond to real-time power controls in the IC structure, causing inefficient usage and/or over-usage of power in the IC structure.